Clock system



March 15, V s HARRISON CLOCK SYSTEM Filed April 25, 1935 INVENTOR Xmgty A TTOR EY Patented Mar; 15, 1938 UNITED STATES PATENT OFFICE CLOCK SYSTEM poration, New York, New York N. Y., a corporation of Application April 25, 1935, Serial No. 18,155

4 Claims.

This invention relates to electric time systems and more particularly to time systems of the type wherein individual secondary clocks are periodically synchronized with a master clock to bring the secondary clocks into unison with each other and the master clock, should there be any variation between them due to unforeseen circuit trouble or interruption of the current supply which operates the system. The invention further relates to the operation of secondary clocks under control of a master clock over power supply circuits normally used for light and power.

It is an object of this invention to provide an electric clock system wherein the secondaries are advanced under the control of a master clock by means of periodic electric impulses of high frequency transmitted over commercial supply lines normally carrying current at lower commercial frequencies.

A further object of the invention is to provide an electric clock system in which secondary clocks are controlled by electric impulses of different frequency characteristics.

Various other objects and advantages of my invention will be obvious from the following particular description of one form of mechanism embodying the invention or from an inspection of the accompanying drawing; and the invention also constitutes certain new and novel features of the construction and combination of parts hereinafter set forth and claimed.

In the drawing:

Fig. 1 shows a wiring diagram of the clock system and diagrammatically shows the essential mechanical features.

Fig. 2 shows a front elevation of a frequency responsive relay used in the control circuit of each clock.

Fig. 3 shows a plan view of the relay in Fig. 2 with certain parts omitted.

Master clock 'The master clock in its general details may be of any desired form such, for example, as is shown in the patent to J. W. Bryce, No. 1,390,018 issued September 6, 1921. Referring to Fig. 1 the master clock includes the usual pendulum operated verge 3 which controls an escapement wheel 4 which is adapted to make one revolution per minute. Mounted on the escape wheel shaft is a cam 5 which cooperates with a pair of contacts 6 causing them to close once each minute for a duration of one second. The usual well known time train, not shown, runs between the escape wheel shaft and the usual hour hand shaft provided in all well known clocks. It is deemed that such mechanism is so well known that it is unnecessary to illustrate it. Mounted on the minute hand shaft are two cams I and 8 which for the purpose of clarity are diagrammatically shown separated. These cams will rotate at the rate of one revolution per hour. Cooperating with cam I are contacts 9, which close at fiftynine minutes and ten seconds after the hour and open at fifty-nine minutes and forty-five seconds after the hour. Cooperating with cam 8 are con tacts ill and II, contact H closing and contact I0 opening at fifty-nine minutes and fifty-five sec onds after the hour and contact Ill closing and contact I i opening at ten seconds after the hour. A contact I E is attached to the verge mechanism which is rocked by a fill-beat pendulum (not shown) causing the contacts 92 to close at every other swing to the pendulum or at the rate of once every two seconds.

Secondary clock The secondary clocks are of the minute impulse type and may be such as shown and described in Patent No. 1,752,939 to J. W. Bryce issued April 1, 1930 and having a magnet designed for A. C. or D. 0. operation in accordance with the commercial current supply in the district where it may be used.

An electric impulse energizes the magnet i3 to advance the minute hand one minute by means of the pawl 14 and ratchet wheel 15. There are sixty teeth in the ratchet'wheel and it requires impulses to advance it one complete revolution, making such revolution in one hours time of normal operation. Fixed to the shaft of the ratchet wheel is a cam l6 which also makes one revolution per hour. Cooperating with these cams are contacts I! and I8. Contact 18 closes and contact i'l opens on the 59th minute position of the secondary, and contact l1 again closes and contact l8 opens on the 60th minute position of the secondary. Adjacent to each secondary is a relay which may be mounted within the casing of the secondary clock or outside of the casing. Such a relay is shown in Fig. 2 and is the subject of my copending application Serial No. 17,246, filed April 19, 1935 in which its detailed construction and operation are fully described. For the purpose of explaining the operation of the present invention it is deemed that a general description of the operation of the relay will suffice. The relay is of a type designed to be responsive to certain frequencies by means of tuned reeds. A main coil I9 is provided through which passes one leg of a square-shaped laminated yoke ll which terminates at pole faces it set closely together. Two reeds 32 and II tuned to vibrate at two definite frequencies extend through the air gap between the pole faces and are anchored and mounted at their lower end on the horizontal leg of the yoke 20. Surrounding these reeds is a biasing coil 84.

Rigid projectons I5 and Ila are fixed to contact arms 38 and a respectively and normally rest on the top of these reeds, there being one rigid projection resting on each reed (Fig. 3). Fig. 2, being a front elevation. shows only the arm 36 and the projection 35 which is on the near side and in the same plane as the other similar parts hidden from view. The contact arm and its cooperating contacts 81 and II are mounted in the usual manner, separated by insulated strips to a supporting structure which also supports the yoke 20. In its normal position contacts 38 are closed and contacts 31 are opened. The biasing coil 34 is constantly energized from the 60-cycle power line and does not affect the reeds. When a current of a certain frequency to which one of the reeds is tuned to respond to is sent through the main coil, resonance is established between the main coil and the biasing coil and the reed is caused to vibrate which moves it out from under the rigid projection 35 allowing the contact arm 30 to drop thereby opening contact 38 and closing contact 31.

When contact 31 closes a circuit is established through the operating magnet II to advance the clock and also through a reset magnet 40 which is mounted on the relay. The reset magnet is of the plunger solenoid type and when energized vdraws the plunger into the coil of the magnet.

The plunger operates on a linkage to which is attached an air dash pot 4| to retard the speed with which this plunger may operate. Through a suitable linkage, described in detail in my copendlng application Serial Number 17,246 an insulated stud '42 moves upward lifting contact arm 88 so that contact 31 opens and contact l0 closes. The opening of contact 31 breaks the circuit through the clock operating magnet ii and the reset magnet ll so that the ratchet pawl l4 and the reset mechanism are restored to their normal positions by means of suitable biasing springs, leaving the contact arm 36 supported by the rigid member 35 resting on the reed 32, the high frequency current through the main coil having now been cut off in a manner which will be explained in the operation of the system.

Operation In the present invention it is proposed to operate the secondary clock units from periodic impulses once each minute of a current of 1200 cycle frequency, and during the synchronizing period to substitute a single impulse of 1800 cycle frequency. For this purpose a double frequency generator is employed which in the diagram is indicated by a motor 50 connected to two generators SI and 52. The generator 5| generating 1200 cycle alternating current and the generator 52 generating 1800 cycle alternating current. The motor is connected across the lines 53 and 54 of a three-wire commercial supply circuit L1, N and L2. A suitable choke coil 55 is introduced into the rounded neutral line N which does not effect the free flow of the 60 cycle commercial current but which does choke back both of the high frequencies against flowing freely to the ground.

With the switch 5. closed the motor 50 is connected across the commercial current line through wires 51 and 50 and ru continuously. The minute impulse contact I n the master clock closing each minute for a period of one second energizes relay magnet 59 each minute through the following circuit. From one side of the supply line 53 through wires 51, 60, contact 8, wire Ii, contact ll, wire 02, relay magnet 59, wires 03, 58, to the other side of the line 54. The energizing of relay magnet 59 causes relay contacts 54 to close and establishing a circuit for the i200 cycle frequency current as foilows:From one terminal of the 1200 cycle generator 51 through wire 65, relay contact 84, wire 86 blocking condenser Ci, wire 51, neutral supply line, wire 54, wire 58, contact 38, blocking condenser 69, main relay coil II to ground connection 10, and through the ground to ground connection ll, wire 12, 13, to the other terminal of the generator 5|.

The effect of this 1200 cycle impulse on the reed that is sensitive to this frequency will cause said reed to vibrate, closing contact 31 and opening contact ll as previously described. A circuit is now established from one side of the line 53 through wire I5, 16, operating magnet l3, wire 11,

contact I'l (now closed) wire 18, contact 31, now closed, wire 50, to the neutral side of the line 54. A parallel circuit is also established from wire, through wire 15,15, reset magnet 40, to wire 11. These parallel circuits receive the regular 60 cycle service as they are not blocked off by condensers, so that the regular commercial power is available for their operation. The blocking condenser 09 blocks out the 60 cycle current from being carried through the main coil l9. It will be observed that the biasing coil 34 is constantly energized from the 60 cycle commercial current line through the following circuit:Supply line 53, wires l5, l9, biasing coil 34, wires 80, 8i, 6., to the supply line N.

All of the secondaries thus are stepped ahead each minute under control of the periodic 1200 cycle impulses. As soon as each secondary reaches its chronological position indicating 59 minutes contact I! opens and contact it closes. This throws the operating magnet l3 into a circult controlled by the contacts 82 and 83 which are controlled by the tuned reed 33 sensitive to 1800 cycle frequency. Thus, if any, secondary unit is fast or in advance of the master clock it will be stopped at its 59th minute position as it can receive no subsequent current impulses controlled by the 1200 cycle frequency impulses.

When any of the secondary units are slow or behind the master clock, provision is made to send out a series of rapid impulses between the 59th and 60th minute indication of the master clock in a similar manner as described in the patent to J. W. Bryce No. 1,687,491, issued October 16, 1920, with the exception that the rapid impulses are of 1200 cycle frequency superimposed over the commercial power lines to the secondary clocks. To initiate such rapid impulses contact 9 in the master clock closes at 59 minutes, 10 seconds, before the hour and opens at 59 minutes, 45 seconds, before the hour. During this 35 second period that this contact is closed the contact I2 which rocks on the verge of the master clock and closes every two seconds will close and open 17 times initiating 17 impulses of 1200 cycle frequency in the following manner. From one side of the line 53, through wires 51, 60, 84, contact 9 now closed, wire 85, contact l2, wire 06; contact i0, wire 62, relay coil 59, wires 63, 58, to the other side of the line 54. The relay coil 58 is thus energized every two seconds from the 60 cycle commercial current closing its contacts 84 at each energization and sending 1200 cycle impulses to the secondary units as previously described. As stated, those secondaries which are on time will not be affected by these rapid impulses due to the opening of contacts I! in the secondaries. Those secondaries which are behind will step forward at each impulse until reaching the 59th minute position at which time their contacts II will open and they will accept no further impulses.

In the present embodiment provision for only 1'7 rapid impulses is made as being a sufficient amount to cover all reasonable variations that might occur in one hour. A greater amount could be used by extending the period of time that the contact 9 is closed or using a double contact on the verge to send out impulses each second. I

With all the secondaries synchronized at their 59th minute position they are ready to receive an impulse to advance them to the 60th minute position. This is accomplished by transmitting to these secondary units an impulse of a different current characteristic which in the present embodiment is a current impulse of 1800 cycle frequency. This is accomplished in the following manner:When the master clock reaches 59' and 55 seconds before the hour contact i opens and contact ll closes. Upon the 60th minute the minute impulse contact 6 closes for one second and establishes the following circuit:From one side of the line 53, wires 51, 68, contact 6, wire 6!, contact ll, wire 81, relay magnet coil 88, wires 89, 63, 58, to the other side of the line 54. The relay magnet coil 88 is thus energized from the commercial 60-cycle current and closes its associated relay contacts 88, establishing a circuit from the 1800 cycle frequency generator as iollows:--From one terminal of generator 52, through relay contacts 80, blocking condenser C2, wire 81, neutral line 54, wires 68, 8|, relay contacts 82, blocking condenser 9|, main coil of tuned reed, relay l8, to ground connections l0 and H to wire 12, to other terminal of 1800 cycle frequency generator 52.

The energizing of the main coil is with 1800 cycle frequency causes the reed 33 to vibrate, thus causing contacts 83 to close and contacts 82 to open. The closure of contacts 83 establishes a circuit as follows:From line 53, through wires 15, 16, operating magnet coil i3, wire 11, contacts l8, now closed, wire 92, relay contacts 83, now closed, wires 8|, 68, to the line 54. The operating magnet I3 is thus again energized from the 60- cycle commercial current as is the reset magnet 40. The 'energization of the reset magnet as previously described opens contacts 83 and closes contacts 82 and thus breaks the circuit through the reset magnet and the operating magnet l3. Upon the deenergization of the operating magnet the secondary is advanced one step to its 60th minute position causing contacts i8 to open and contacts II to close, thus putting the secondary in condition again to be advanced under the control of the normal periodic impulses of 1200 cycle frequency.

While the fundamental and novel features of the invention as applied to a single modification have been shown and described and pointed out, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. I intend to be limited therefore only as indicated by the scope of the following claims.

What is claimed is as follows:-

1. An electric time system'including one or more electric clocks operated by periodic electric current impulses, each current impulse being of a normal commercial current frequency supplied from power lines carrying commercial current supply, means for impressing current impulses of different frequency characteristics on said power line, resonant means in said clocks responsive to a current impulse of a certain frequency characteristic different than said commercial current frequency, means operable by said resonant means for controlling the transmission of a current impulse of commercial current frequency to said clocks to operate the same, synchronizing means in said clocks including means for interrupting the operation of said clocks when they reach a certain chronological condition, other resonant means in said clocks responsive to a current impulse of another frequency characteristic different from said certain frequency characteristic and said commercial current frequency, and means operable by said last named resonant means for controlling the transmission of a current impulse of commercial frequency to said clocks to resume operation of the same.

2. In a distribution system for power and lighting purposes having a neutral conductor, in combination, a clock system including a master clock and one or more secondary clocks connected to said distribution system, a source of power supply for supplying current of different frequency characteristics connected to the neutral conductor, means controlled by the master clock for transmitting electric current impulses of different frequency characteristics at regular time intervals from said source of power supply over said neutral conductor, a plurality of resonant means in said secondary clock operable by current impulses initiated by said master clock, and a ground return circuit from said resonant means to said source of supply, each resonant means being responsive to current of a different frequency characteristic, means controlled by the resonant means for normal, operation of the clock, and synchronizing said clocks with respect to the master clock and impeding means in said neutral conductor for restraining the flow of current of certain frequencies to certain parts of the power distribution system.

3. A clock system including a master clock and one or more secondary clocks, power lines normally carrying current of commercial frequency connected to said secondary clocks and extending to said master clock, means controlled by said master clock for periodically supplying impulses of current of different frequency characteristics to said power line, synchronizing means in the secondary clocks for synchronizing said clocks with respect to the master clock, said means including means for utilizing impulses of current of one frequency characteristic for initiating impulses of current of commercial frequency to normally advance said clocks and to periodically advance them into synchronization with the master clock when they are slow, and means controlled by each clock for interrupting clock advance when said clock reaches a certain chronological condition in advance of the master clock, and means for utilizing an impulse of current of another frequency for initiating an impulse of current of commercial frequency to resume normal operation of said clocks.

4. In a distribution system for power and lighting purposes including an ungrounded conductor and a grounded return conductor normally carrying current of commercial frequency. in combination, a clock system including one or more secondary clocks connected to said conductors and operated by the current of commercial frequency carried thereby, a source oi power-connected to said grounded conductor only for supplying current of frequency characteristics different from said commercial frequency current to said conductor, a choke coil in said grounded conductor disposed between the ground and said source of power for preventing the passage of said current of different frequency characteristics to the ground of the grounded conductor, a

master clock for controlling the transmission of electric current impulses of said diiferent frequency characteristics at regular timed intervals from said source of supply to said grounded conductor, resonant means in each secondary clock connected to said grounded conductor and responsive to the timed controlled impulses of different frequency characteristics transmitted over said grounded conductor, a return ground circuit from said resonant means to the source of supply. and means controlled by said resonant means for initiating current impulses of said commercial frequency transmitted over said grounded and ungrounded conductors for advancing the cloth and for synchronising them with the master clock.

LAURENCE 8. HARRISON. 

